Linear applications in cleanrooms


Linear applications in cleanrooms place special demands on the included components. So, what do you need to consider when designing and selecting products for cleanroom applications? By having a good understanding about the causes of unwanted particles and how they appear, you can easily design your solution accordingly.

Strict demands on the surrounding environment

In cleanrooms, there is a controlled level of contamination. In normal cases, the focus is often on avoiding contamination from the environment getting into linear components, such as e.g. rail guides and ball screws, but in cleanrooms the opposite applies – to avoid these components introducing contaminants into the cleanroom environment. Cleanrooms are usually associated with the electronics and medical industry, but also occur for certain applications in the aviation, pharmaceutical and food industries.

Friction – the enemy of the cleanroom

Moving linear rail guides inevitably create small particles due to the friction that occurs between the various surfaces that come into contact with each other during the movement. Since the goal is to keep the amount of unwanted particles to a minimum, the focus should be on reducing friction as much as possible. A linear guide with balls or rollers, such as a ball bushing or ball screw, is therefore preferable to a sliding bushing or sliding screw.

Seals, lubrication & ball chain

Common standard seals on linear rail guide blocks or ball screws nut tend to generate some friction when moving. Low-friction seals or seals that have no contact with the rail/ball screw are therefore preferred in cleanrooms. However, these seals have a disadvantage as they have a greater risk of lubricants leaking into the surrounding environment. You should therefore use special types of lubricants that are approved for use in a cleanroom environment.

It has recently been proven that linear rail guides with ball chains reduce the amount of unwanted particles forming. The ball chain separates the balls in the block and prevents them from coming in contact with each other.

Ball chain comparison

Choose stainless material

Preferred materials in a cleanroom environment are usually stainless steel and PVC. Many miniature rail guides and miniature ball screws are available in stainless steel, making them a good option for cleanroom applications. These also often come with low-friction seals and low preload as standard.

Although plain steel and aluminium are often standard materials in linear components, there are ways to adapt them to cleanrooms. Steel can, for example, be surface treated by chrome plating or nickel plating, which prevents oxidation. Aluminium can in some cases be anodized, which gives the surface a comprehensive corrosion protection by strengthening the aluminium's natural oxide layer.

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